Various forms of mine roof anchors and rock bolts have been heretofore provided for anchoring in mine roofs and other rock formations. However, most earlier mine roof anchors and rock bolts utilized expandable anchors while more recent development in rock bolts and mine roof anchors has turned toward using grout (in different forms) to anchor a mine roof anchor or rock bolt to the associated rock or other ground formation.
These later forms of anchors and bolts are operative in a superior manner at relatively low cost, but in many instances the anchor or bolt may not be readily subject to proper tensioning after a grouting operation has been completed.
Examples of various forms of anchors and rock bolts including some of the general structural and operational features of the instant invention are disclosed in U.S. Pat. Nos. 3,336,758, 3,379,016, 3,695,045 and 3,893,303.